This invention is related to machine readable information carriers, and, in particular, to a manufacturing and inventory control card for carrying one or more microelectronic memory devices having a non-volatile, erasable, and programmable memory capability.
Management information systems are widely used for monitoring business operations, especially order entry, manufacturing and inventory control. Such systems include a central computer that is programmed to monitor an order for a product from the initial receipt of the order, through manufacture of the ordered item, until the order is completed by delivery to the customer. Such programmed computers are capable of initiating orders for component parts, if the inventory information available indicates such orders are needed. The computer can also maintain information about the amount and kind of labor and material put into the order so that accurate cost accounting can be maintained.
It is desirable to have a tangible record of machine (computer) readable information physically accompany an order through its various stages of manufacture, assembly, processing and delivery. Such tangible record should include information about the desired characteristics of the ordered entity and be capable of storing data about the entity as the order progresses. Such an information carrier should be durable, capable of withstanding a manufacturing environment, compact, and easy to use.
Punched cards or punched paper tape are typical customary information carriers. But cards and tape are not well suited to manufacturing environments. They are easily damaged or destroyed. Moreover, complex computer systems require more information than can be contained on one card or a short paper tape. So, multiple cards or long tapes are needed, thereby further complicating the handling of such items.
Another well-known information carrier is a magnetic tape cassette. These are small in size and can hold a lot of information. However, experience with such cassettes shows they are highly sensitive to dirt and moisture that are typically present in a manufacturing environment. Magnetic cards are less sensitive to the environment, but they have limited storage capacity. Information on the cards is easily erroneously altered or destroyed when the cards are exposed to spurious magnetic fields that are often found around electrical motors that operate manufacturing machines.
Advances in the state of the art of microelectronics have made available a number of small devices adaptable for information carriers in the manufacturing process. Random access memory (RAM) devices are capable of receiving, storing and deleting data. However, such devices are volatile, depend upon a continuous supply of voltage and all stored information is lost if the voltage supply is interrupted or disconnected. Other, non-volatile devices, such as PROMs (programmable readonly memories) are non not erasable. Information can be entered into a PROM and the PROM will retain the information, even in the event of a power failure. However, since a PROM can only be used once, it would be too expensive and not a practical information carrier for a management information system.